Method and apparatus for germanium reclamation from chemical vapor deposition

Abstract

A continuous system recovers germanium (Ge) from a chemical vapor deposit. A chemical vapor deposit scrubber scrubs a chemical vapor deposit to form a chemical vapor deposit scrubber solution. An equalization and neutralization mixer adds a caustic soda to the chemical vapor deposit scrubber solution to form an equalization and neutralization mixer solution having a pH above 12.0 to maintain the solubility of silicon oxide (SiO 2 ) and hypochlorite (ClO - ). A hypochlorite reduction mixer adds a peroxide to the equalization and neutralization solution to form a hypochlorite reduction solution to reduce hypochlorites. A precipitant and neutralization mixer adds a metal cation such as Epsom Salts (MgSO 4 ) and a caustic soda, such as sodium hydroxide (NAOH), to the hypochlorite reduction solution to form a precipitant and neutralization solution to precipitate magnesium germanate (MgGeO 3 ) and magnesium metasilicate (MgSiO 3 ). A reactor tank adds a polymer to the precipitant and neutralization solution to flocculate the germanium (Ge) and silicon (Si) solids and form a flocculation solution. A plate clarifier collects the flocculation solution to form a flocculated material. A filter press and the dryer produces a dry sludge of germanium (Ge) within a range of 5%-10% by weight.

We claim: 
     
       1. A process for recovering germanium from a chemical vapor deposit exhaust, comprising the steps of: scrubbing the chemical vapor deposit exhaust to form a scrubber solution having gaseous and particulate germanium material and silicon oxide and hypochlorite therein;   equalizing and neutralizing the scrubber solution to form an equalized and neutralized germanium solution having a required pH to maintain the solubility of the silicon oxide and hypochlorite therein;   reducing hypochlorites in the equalized and neutralized germanium solution to form a hypochlorite reduced germanium solution;   precipitating and neutralizing the hypochlorite reduced germanium solution by adding a metal cationic salt to form a precipitated and neutralized solution having a cationic germanate salt and a cationic metasilicate salt therein;   flocculating the precipitated and neutralized solution to aggregate germanate and metasilicate solids therein to form a flocculation solution;   collecting the flocculation solution and forming a flocculated material;   drying the flocculated material to produce a dry sludge of germanium; and   forming the dry sludge into filter cakes for recycling.   
     
     
       2. A process according to claim 1, wherein the metal cationic salt is magnesium sulfate;   wherein the cationic germanate salt is magnesium germanate salt; and   wherein the cationic metasilicate salt is magnesium metasilicate salt.   
     
     
       3. A process for recovering germanium from a chemical vapor deposit exhaust, comprising the steps of: scrubbing the chemical vapor deposit exhaust to form a scrubber solution having gaseous and particulate germanium material and silicon oxide and hypochlorite therein;   equalizing and neutralizing the scrubber solution to form an equalized and neutralized germanium solution having a required pH to maintain the solubility of the silicon oxide and hypochlorite therein;   reducing hypochlorites in the equalized and neutralized germanium solution to form a hypochlorite reduced germanium solution;   precipitating and neutralizing the hypochlorite reduced germanium solution by adding magnesium sulfate to form a precipitated and neutralized solution having a magnesium germanate and a magnesium metasilicate therein;   flocculating the precipitated and neutralized solution to aggregate germanate and metasilicate solids therein to form a flocculation solution;   collecting the flocculation solution and forming a flocculated material;   drying the flocculated material to produce a dry sludge of germanium; and   forming the dry sludge into filter cakes for recycling.   
     
     
       4. A process according to claim 3, wherein the step of equalizing and neutralizing includes using an equalization and neutralization mixer and providing a caustic soda to the scrubber solution to form the equalized and neutralized germanium solution and maintain the solubility of the silicon oxide and the hypochlorite therein.   
     
     
       5. A process according to claim 4, wherein the equalized and neutralized germanium solution has a pH above 12.0.   
     
     
       6. A process according to claim 3, wherein the step of reducing hypochlorites includes using a hypochlorite reduction mixer and providing a hydrogen peroxide to the equalized and neutralized germanium solution to form the hypochlorite reduced germanium solution.   
     
     
       7. A process according to claim 3, wherein the step of precipitating and neutralizing includes using a precipitant/neutralization mixer and providing a metal cation and a caustic soda to the hypochlorite reduced germanium solution to form the precipitated and neutralized solution.   
     
     
       8. A process according to claim 7, wherein the metal cation is added to aid in the precipitation of the magnesium germanate and the magnesium metasilicate in the precipitated and neutralized solution; and   wherein the caustic soda is added to neutralize the precipitated and neutralized solution.   
     
     
       9. A process according to claim 7, wherein the metal cation is Epsom Salts and the caustic soda is sodium hydroxide (NaOH).   
     
     
       10. A process according to claim 3, wherein the step of flocculating includes using a reactor tank for holding the precipitant/neutralization solution and adding a cationic polymer thereto to aggregate the germanate and metasilicate solids to form the flocculation solution.   
     
     
       11. A process according to claim 3, wherein the step of collecting includes using a clarifier, including a plate or chevron clarifier, to form the flocculated material.   
     
     
       12. A process according to claim 3, wherein the step of processing and drying includes using a filter press and a dryer to produce the dry sludge of germanium.   
     
     
       13. A process according to claim 3, wherein the step of collecting includes using a clarifier, including a plate or chevron clarifier, to form the flocculated material; and   wherein the step of processing and drying includes using a filter press and a dryer to produce the dry sludge of germanium.   
     
     
       14. A process according to claim 13, wherein the process further comprises the step of recycling and returning supernate from the plate clarifier and excess water from the filter press to another system.   
     
     
       15. A process according to claim 3, wherein the process further comprises the step of running continuously the steps of the process.